Emerson Process Management 8732 High Process Noise Detection, Turning High Process Noise On/Off

Reference Manual

00809-0100-4663, Rev BA January 2010

Rosemount 8732

Troubleshooting Ground/Wiring Fault

Ground/Wiring Fault Functionality

The transmitter detected high levels of 50/60 Hz noise caused by improper wiring or poor process grounding.

1.Verify that the transmitter is earth grounded.

2.Connect ground rings, grounding electrode, lining protector, or grounding straps. Grounding diagrams can be found in “Grounding” on page 5-12.

3.Verify sensor is full.

4.Verify wiring between sensor and transmitter is prepared properly. Shielding should be stripped back less than 1 in. (25 mm).

5.Use separate shielded twisted pairs for wiring between sensor and transmitter.

6.Properly connect the wiring between the sensor and the transmitter. Corresponding terminal block numbers in the sensor and transmitter must be connected.

The transmitter continuously monitors signal amplitudes over a wide range of frequencies. For the Ground/Wiring Fault diagnostic, the transmitter specifically looks at the signal amplitude at frequencies of 50 Hz and 60 Hz which are the common AC cycle frequencies found throughout the world. If the amplitude of the signal at either of these frequencies exceeds 5 mV, that is an indication that there is a ground or wiring issue and that stray electrical signals are getting into the transmitter. The diagnostic alert will activate indicating that the ground and wiring of the installation should be carefully reviewed.

HIGH PROCESS NOISE DETECTION

The High Process Noise diagnostic detects if there is a process condition causing unstable or noisy readings, but the noise is not real flow variation. One common cause of high process noise is slurry flow, like pulp stock or mining slurries. Other conditions that cause this diagnostic to activate are high levels of chemical reaction or entrained gas in the liquid. If unusual noise or variation is seen, this diagnostic will activate and deliver a PlantWeb alert. If this situation exists and is left without remedy, it will add additional uncertainty and noise to the flow reading.

Turning High Process Noise On/Off

375Transducer Block, Diagnostics, Diagnostic Controls AMS Tab Diagnostics

The High Process Noise diagnostic can be turned on or off as required by the application. If the advanced diagnostics suite 1 (D01 Option) was ordered, then the High Process Noise diagnostic will be turned on. If D01 was not ordered or licensed, this diagnostic is not available.

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